On its Web site, the airline apologized for the disruption and suggested that customers seek alternative travel arrangements.

The company had over 2,200 employees, Mr. Freitag said.

“Virtually all of ATA’s employees are being notified today that their positions are eliminated,” Mr. Freitag said.

The carrier retrenched in 2006 after emerging from bankruptcy protection, focusing on destinations in the Southwest and an increase in military charter business. But like other airlines, it has struggled amid an economic slowdown and has been unable to offset soaring fuel prices.

Fuel is one of the industry’s top costs and has pushed some carriers into merger talks.

Major airlines, to offset record fuel prices, have slashed amenities that were once free and added fees for second bags, traveling with pets and booking tickets by phone.

United Airlines said new luggage fees it had imposed on travelers will generate more than $100 million a year.

ATA came out of bankruptcy with several other carriers two years ago, and it became the second to declare bankruptcy in the last two weeks, both with operations in Hawaii. Aloha Airlines filed for bankruptcy protection last month, a little more than two years after emerging from bankruptcy.

ATA announced last month that it would leave Chicago’s Midway Airport, which it had used as a hub since 1992.

The chief executive officer at ATA’s parent company resigned two weeks ago. Subodh Karnik, who had been chief executive, stepped down after heavy pressure from a major investment firm to turn the airline around.